Here is the full list of all 60 Legend of Grimrock 2 achievements.
Complete the game with Ironman and Single-use Crystals modes turned on
Complete the game with hard difficulty setting
Complete the game with old school mode
Max out three skills
Learn 15 spells
Reach level 10 with a farmer
Summon the Viper Roots in under 6 minutes
Defeat a monster with a backstab attack
Kill a monster by throwing pants at it
Polymorph 10 times
Find all secrets
Dig up all treasure chests
Find the Relic
Find 8 skulls
Enter the Nexus
Enter the Shrine of Balance
Collect and wear rogue's wardrobe (5 pieces)
Visit all levels
Defeat the Lindworm
Perform 500 missile or throwing weapon attacks
Collect and wear full set of Crystal armor (6 pieces)
Collect and wear full set of Meteor armor (6 pieces)
Defeat a Magma Golem
Collect and wear archmage's uniform (4 pieces)
Find the pie
Defeat the Wormbound brothers
Enter the Castle
Collect four elemental essences
Find Bane
Perform 100 power attacks
Open 5 gold locks
Find 50 secrets
Assemble the Meteor Hammer
Enter the Pyramid of Umas
Open the gate to the Cemetery
Enter the Crystal Mines
Defeat the Ratling Boss
Max out a skill
Kill a monster with a single blow
Open the door to the Archives
Kill 250 monsters
Mix a total of 50 potions
Cast 500 spells
Find 25 secrets
Catch 25 fish
Defeat Herder's Den
Visit 10 levels
Dig up three treasure chests
Dive 250 tiles
Travel 10000 tiles
Kill a monster by teleporting on it
Deal a killing blow with unarmed attack
Cast 250 Spells
Defeat the Summon Stones
Collect an elemental essence
Perform 500 melee weapon attacks
Find 10 secrets
Mix a total of 10 potions
Defeat the Viper Roots
Cast 25 spells